1. Field of the Invention
The present invention relates to a seatbelt device comprising a buckle pretensioner for fastening a seatbelt to a passenger by retracting the buckle upon situations such as a sudden deceleration of a vehicle.
2. Description of the Related Art
Conventionally, as means for fastening a seatbelt to a passenger upon situations such as a sudden deceleration of a vehicle, other than a belt tension device arranged on the retractor side of the seatbelt, used was a buckle pretensioner for retracting toward the lower part of the vehicle body a buckle to be engaged with.a tongue plate mounted on the midway position of the seatbelt.
This conventional buckle pretensioner, for example, retracts the buckle by retracting toward the lower part of the vehicle body a connective member such as a steel plate, rod, wire, webbing, or tape provided for fixing the buckle to the vehicle body or seat, etc. The buckle pretensioner thereby exhibits its function as a securing device by securing a passenger to the seat with such operation.
Here, if the buckle pretensioner is structured to be capable of retracting the buckle toward the lower part of the vehicle body in a straight line, the structure thereof could be made with an extremely simple mechanism. Generally speaking, however, a buckle pretensioner is usually installed in the space between the seat and center console. Thus, in consideration of the fact that the installation space is small, and in order to secure the comfortableness and safety of rear-seat passengers and to improve the outward appearance of the vehicle interior, the buckle pretensioner is devised such that the connective member is folded back via a pulley, for example, to change the retractive direction thereof.
In order to change the retractive direction of a connective member, a certain degree of freedom (adjustability) is required regarding the xe2x80x9cfoldingxe2x80x9d of such connective member. Thus, adopted as the material for the connective member used in existing products is, for the most part, a wire member or tape member including a webbing.
A connective member is often retained with a retractor (specifically, for example, a piston activated by the pressure of the combustion gas inside the cylinder) which retracts the buckle and comprises a structure of retracting the buckle by being pulled by such piston. Accordingly, the connective member retracts the buckle upon being exposed to the combustion gas inside the cylinder.
Furthermore, conventional buckle pretensioners are disclosed, for example, in Japanese Utility Model Laid-Open Publication No. Sho 50-83718, Japanese Utility Model Laid-Open Publication No. Hei 6-35061, Japanese Patent Laid-Open Publication No. Sho 49-61822, and so on.
The buckle pretensioners described in Japanese Utility Model Laid-Open Publication No. Sho 50-83718 and Japanese Utility Model Laid-Open Publication No. Hei 6-35061 have both the connective member and pulleyxe2x80x94or only the connective memberxe2x80x94arranged inside the cylinder, and comprise the structure of changing the retractive direction by converting the direction of the connective member with the pulley.
The buckle pretensioner described in Japanese Patent Laid-Open Publication No. Sho 49-61822 comprises a direct-acting structure using a rod as the connective member.
Moreover, the conventional buckle pretensioner shown in FIG. 24 comprises a structure wherein a gas generator 319 for filling combustion gas into the combustion gas chamber 320 and a driving member 310 for retracting the buckle 311 are provided at separate locations. Specifically, the component for mounting the gas generator 319 is composed of a die-cast product, a cylinder 315 is mounted thereon and, for example, a piston 316, a hook member 317 for preventing reverse operations, and a wire rope 313 are partially housed in such cylinder 315.
In addition, reference numerals 322, 325, 327, and 335 denote an O-ring, cap, ball, and base, respectively. Reference numeral 314 is a pulley for changing the direction of the wire rope 313.
With conventional buckle pretensioners, it is usually necessary to hermetically seal the cylinder for efficiently converting the combustion gas pressure into retractive power to retract the buckle. Nevertheless, a method widely adopted is to provide a through hole to the cylinder for retracting the connective member or piston rod and, thus, there is a possibility that the combustion gas will leak therefrom. Although measures such as using sealing members to achieve airtightness are being taken, it is not possible to completely prevent gas leakage, and the actual condition is that the retractive efficiency is lowered thereby.
In the buckle pretensioner described in Utility Model Laid-Open Publication No. Sho 49-61822, there is particular concern that the combustion gas generated upon the retraction of the buckle will blow out, in no small quantities, from the rear seat side. Moreover, depending on the setting of the retractive stroke of the piston, there is a possibility that the buckle pretensioner may interfere with the vehicle floor.
Conventional connective members changing the retractive direction such as those described in Japanese Utility Model Laid-Open Publication No. Sho 50-83718 and Japanese Utility Model Laid-Open Publication No. Hei 6-35061 are structured from a wire member or tape member, and are exposed to combustion gas. Therefore, upon endeavoring to improve the durability of such connective members, there is a problem in that the costs therefor and the weight thereof will increase.
Moreover, as the buckle pretensioner shown in FIG. 24 comprises a structure wherein the driving mechanism 310 for retracting the buckle 311 and the gas generator 319 are arranged at separate locations, the shape of the component for mounting the gas generator becomes complex. It is therefore necessary to manufacture such component with the die-cast method, and this will lead to high production costs.
The present invention aims at resolving the aforementioned conventional problems, and an object thereof is to provide a seatbelt device comprising a buckle pretensioner capable of preventing a connective member from being subject to high temperature/pressure and efficiently converting combustion gas pressure, which provides pressure for retracting the buckle, into retractive power.
Another object of the present invention is to provide a seatbelt device comprising a buckle pretensioner realizing the simplification in the shape of structural components and the reduction of manufacturing costs.
In order to achieve the aforementioned objects, the present invention provides a seatbelt device comprising a buckle pretensioner, wherein the buckle pretensioner includes: a retractor for retracting the buckle pursuant to the combustion gas pressure of powder; and a connective member for connecting the retractor and the buckle; and wherein the connective member is arranged in a position such that it is not exposed to the combustion gas.
The buckle pretensioner of the seatbelt device comprising this structure is capable of preventing the connective member from being subject to high temperature/pressure as the connective member is arranged in a position such that it is not exposed to the combustion gas. Moreover, as the connective member is not inserted into the combustion gas chamber (a cylinder for example) to which the combustion gas is filled, this gas chamber may be made airtight. It is therefore possible to efficiently convert the combustion gas pressure into retractive power of the buckle.
The buckle pretensioner of the seatbelt device of the present invention, for example, may have a multistage structure of converting the combustion gas pressure into extrusive power and then converting this extrusive power into retractive power of the buckle.
More specifically, the buckle pretensioner of the seatbelt device according to the present invention may be of a structure wherein the retractor includes: a cylinder; a gas generator for supplying combustion gas into the cylinder; a piston movably housed inside the cylinder; and a rod connected to the piston and connected to the connective member; wherein the retractor retracts the buckle by extruding the piston and rod pursuant to the pressure of the combustion gas supplied from the gas generator.
Here, the connection of the piston and the rod includes cases wherein the piston and rod are formed integrally, formed separately and connected, and formed separately and connected via an intervening member, for example.
Furthermore, the retractor may include: a gas generator for supplying combustion gas into the cylinder; and a bag expandably fixed to the cylinder by being connected thereto via through holes and further connected to the connective member; and wherein the retractor retracts the buckle by expanding the bag pursuant to the combustion gas supplied from the gas generator.
The gas generator may be arranged on the axis of the moving direction of the rod. The gas generator may also be arranged on the axis of the expanding direction of the bag. Or the gas generator may be arranged on the axis of the extruding direction of the connective member.
A running block may be provided to the tip of the rod such that the buckle is retracted upon the connective member being moved via the running block. A combination of guides or a groove for preventing the disengagement of the connective member during vehicle movement may be provided to the running block. As a matter of course, a disengagement-prevention structure (guide, groove, etc.) may be jointly used or formed integrally with the connective member.
Instead of the aforementioned running block, a member with an R-shaped face in contact with the connective member may also be used.
An oxidizer or pro-oxidant (catalyst) for reducing carbon monoxide gas contained in the combustion gas may be arranged between the piston and the gas generator.
The buckle pretensioner comprising this structure has the driving mechanism (piston and connective member for example) and the gas generator for generating combustion gas arranged in the same housing and, therefore, the manufacture of separate components for mounting the gas generator as in conventional devices is not necessary. Thereby, complex shapes of structural components are no longer required, a low production cost is realized, and the reliability is increased.
The aforementioned same housing, for example, could be a cylinder or housing, but is not particularly limited thereto.